import java.util.Scanner;

public class demo01 {
    Scanner scanner = new Scanner(System.in);
    public  static void san(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入三角形的底：");
        double a = scanner.nextDouble();
        System.out.println("请输入三角形的高：");
        double b = scanner.nextDouble();
        System.out.println("三角形的面积为："+(a*b)/2);
    }
    public  static void zheng(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入正方形的长：");
        double c = scanner.nextDouble();
        System.out.println("正方形的面积为："+(c*c));
    }
    public  static void chang(){
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入长方形的长：");
        double m = scanner.nextDouble();
        System.out.println("请输入长方形的宽：");
        double n = scanner.nextDouble();
        System.out.println("三角形的面积为："+(m*n));
    }
    public static void san2(double a , double b){
        System.out.println("三角形的面积为:"+(a*b)/2);
    }
    public static void zheng2(double d ){
        System.out.println("三角形的面积为:"+(d*d));
    }
    public static void chang2(double e , double f){
        System.out.println("三角形的面积为:"+(e*f));
    }
    public static double san3(double g , double h){
        return g*h;
    }
    public static double zheng3(double i){
        return i*i;
    }
    public static double chang3(double j,double k){
        return j*k;
    }

}
